The Preparation And Property Of Hydroxypropyl Starch As An Environmental Friendly Fluid Loss Reducer

Hydroxypropyl starch(HPS) is a type of green chemical which is synthesized from starch.It could be widely used in many fields, such as food, textile, paper and so on. And it have the effect of well-bore stability, flocculating drilling cuttings and filtration. But its performance is not satisfactory. So it is very important for us to explore a new type of preparation techniques which could prepare the hydroxypropyl starch with lower cost and higher performance. Also,it is necessary for us to make a systematic research on its low fluid loss performance.The reaction conditions of solvent method was optimized by orthogonal test and single-factor test, used corn starch and propylene oxide. The result shows that the reaction temperature has a maximum effect on performance of product, and the amount of propylene oxide takes the second place while the starch slurry concentration has the least effect. The optimum condition of hydroxy-propylation reaction are as follows: reaction temperature 60℃,reaction time 20 h, the amount of propylene oxide 30%(compared to the weight of starch), the amount of sodium hydroxide 0.7%(compared to the weight of starch), starch slurry concentration 45%. The product could resist high temperature up to 140℃ in 4% NaCl salt water muds. A novel preparation techniques--half-dry method was studied. The result shows that the reaction temperature has a maximum effect on performance of product, and the amount of propylene oxide takes the second place while the amount of sodium hydroxide has the least effect. The optimum condition of hydroxy-propylation reaction in half-dry method are as follows: reaction temperature 55℃, reaction time 8h, the amount of propylene oxide38%, the amount of sodium hydroxide 1.4%, water content in reaction system 31%. Theproduct could resist high temperature up to 150℃ in 4% NaCl salt water muds. The product was characterized by IR and SEM.The low fluid loss performance of self-made product by solvent method and half-dry method product were studied according to the standard for modified starch in GB/T5005-2010. The resistance of the product to salt, calcium and magnesium were investigated,and the performance comparison between self-made product and other kinds of fluid loss reducer were tested. Finally, the compatibility with antioxidant, viscosity reducer and other kinds of fluid loss reducer were examined by compositional experiment. It shows that product made by solvent method could resist salt concentration up to 10% at the temperature of 140℃.And it could be used in the operating environment that the maximum content of Ca2+ and Mg2+was 360mg/L and 240mg/L, respectively. The product made by half-dry method could resist high temperature up to 150℃ in 4% NaCl salt water muds; At the temperature of 150℃,it could resist salt concentration up to 4%, and it could be used in the operating environment that the maximum content of Ca2+ and Mg2+ was 360mg/L and 180mg/L, respectively. We concluded that the product made by solvent method have better performance than the product made by half-dry method. And the self-made product is better than commercial product. SL and EFF is the best choice as a complex agents. The API filtration in 4% NaCl salt water muds is reduced to 6.8mL from 7.4mL after being aged at 150℃ for 16 h when compounded,and the resistance to salt, calcium and magnesium is improved.The product begin to have the good low fluid loss performance when MS is over 0.2. But the performance is not improved as the MS increased. The reaction conditions and the uniformity of substituent group in starch molecule also play an important role in fluid loss performance of HPS. The absorption between HPS and clay play an important role in filtration control of HPS.